[PATCH 5.10 332/406] NFS: Fix a potential data corruption

Greg Kroah-Hartman
2023-09-17T19:39:08Z

From: Trond Myklebust <trond.myklebust@hammerspace.com>

commit 88975a55969e11f26fe3846bf4fbf8e7dc8cbbd4 upstream.

We must ensure that the subrequests are joined back into the head before
we can retransmit a request. If the head was not on the commit lists,
because the server wrote it synchronously, we still need to add it back
to the retransmission list.
Add a call that mirrors the effect of nfs_cancel_remove_inode() for
O_DIRECT.

Fixes: ed5d588fe47f ("NFS: Try to join page groups before an O_DIRECT retransmission")
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/nfs/direct.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)

--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -509,13 +509,31 @@ out:
return result;
}

+static void nfs_direct_add_page_head(struct list_head *list,
+ struct nfs_page *req)
+{
+ struct nfs_page *head = req->wb_head;
+
+ if (!list_empty(&head->wb_list) || !nfs_lock_request(head))
+ return;
+ if (!list_empty(&head->wb_list)) {
+ nfs_unlock_request(head);
+ return;
+ }
+ list_add(&head->wb_list, list);
+ kref_get(&head->wb_kref);
+ kref_get(&head->wb_kref);
+}
+
static void nfs_direct_join_group(struct list_head *list, struct inode *inode)
{
struct nfs_page *req, *subreq;

list_for_each_entry(req, list, wb_list) {
- if (req->wb_head != req)
+ if (req->wb_head != req) {
+ nfs_direct_add_page_head(&req->wb_list, req);
continue;
+ }
subreq = req->wb_this_page;
if (subreq == req)
continue;